Badgers: the debate continues

The threat of bovine TB to cattle is still as great as ever, with the latest statistics release from Defra highlighting its continued presence. The use of badger culling to attempt to reduce the incidence of disease across the country was first announced in 2011, and was set to go ahead in autumn 2012. After difficulties with the policy, and the realisation that the originally calculated badger numbers were not accurate, however, the culls were postponed.  Natural England reissued badger cull licences last month for Gloucestershire and Somerset and culls are now set to start from June. The policy has been seen as controversial since its inception.

A meeting of the Wildlife and Conservation all-party parliamentary group (APPG) on Wednesday brought together proponents both ‘for’ and ‘against’ the cull for a lively debate. On one side were Adam Quinney (Vice President, National Farmers’ Union) and Sir Jim Paice MP (former Defra minister), and on the other, Simon King (President of the Wildlife Trusts) and Dr Brian May (founder of Save Me).

Sir Jim Paice started the debate by highlighting the prevalence of bTB in cattle across the UK, emphasising that this was a huge issue that has knock-on effects for the whole country. To tackle this problem, Defra has proposed a ‘toolbox’ of measures over the years, with badger culling only forming a part of this. Sir Jim Paice recognised that the long-term, well-designed Randomised Badger Culling Trial (RBCT) represents the best science available to use as a base for forming policy around a badger cull. Led by Lord Krebs, the trial lasted from 1997-2007, and was overseen by an Independent Scientific Group (ISG) on bTB. As outlined in a previous blog post, proactive culling (culling across all accessible land) was seen to reduce the incidence of bTB in cattle, but this was offset by perturbation – the increased movement of badgers to other areas after their social groups are disrupted. The trial showed a net benefit of a 16% reduction in bTB incidence through badger culling over a sustained nine year period. This figure, in addition to the knowledge that cases increase after culls have stopped led the ISG to conclude that “badger culling cannot meaningfully contribute to the control of cattle TB in Britain.”

Despite these strong recommendations from an experienced body of scientists, a badger cull was scheduled to go ahead. Using the RBCT as a base, Defra altered the methods to try to reduce costs and improve efficacy. In comparison to the RBCT, the pilot culls will be industry-led, not government-led; badgers will not be cage-trapped before shooting; a wider area will be used; and culling will only be carried out in areas surrounded by hard barriers to prevent perturbation.

Adam Quinney spoke of the wildlife policies present in every country with bTB, bringing up New Zealand as a good example. The differences between both the disease and policy in the England and New Zealand are quite marked, however. In NZ, possums act as TB reservoirs. Unlike badgers, these are an invasive species and are able to be culled or even eradicated from areas. In addition to spreading bTB, they also present threats to native wildlife, justifying their control. This is not the case with badgers in England, as it is a native species. Control of possums is also carried out across the whole country. In areas where this is relaxed, opportunistic infection has been shown to enter. This is similar to the perturbation effect seen in the RBCT, and presents a problem for the pilot badger culls set to go ahead in England.

Brian May spoke of the planned cull as an “impending tragedy”, reminding all that Lord Krebs himself has called the cull “a crazy scheme.” The flaws in the interpretation of the available scientific data and the process of science by Government and others were highlighted, including Sir David King’s (the Government Chief Scientific Adviser in 2007) report from the ISG review. Here, he concluded that “a programme for the removal of badgers could make a significant contribution to the control of cattle TB…provided removal takes places alongside an effective programme of cattle controls.” Brian May noted that this was condemned by Nature and was not subject to peer-review, but still accepted by Government as an authoritative document.

May reminded all that the pilot culls are not a scientific experiment, and therefore no meaningful conclusions about the methods of culling used can be drawn from the results. Many parameters have been altered, and no control area will be used for comparison. Sir Jim did recognise this, but did not seem concerned that the pilots would simply be an isolated exercise.

May also highlighted concerns about the estimates that have been made of the sizes of badger populations. These are needed to comply with the Bern Convention, as culling activities cannot render badgers locally extinct. They also allow the total percentage of badgers culled overall to be gauged. Estimates of population sizes over the past year have varied hugely, and the lack of accurate data led the culls to be postponed last autumn. A report to Natural England at the end of February used sett surveys and hair trapping to estimate badger numbers in the pilot areas. Population estimates (with 80% confidence levels) were 2657-4079 for Gloucestershire and 1972-2973 for Somerset. These are extremely wide-ranging, and do not lead to certainty that the recommended level of 70% of badgers will be killed in culls. As Donnelly and Woodroffe highlight in a correspondence in Nature, this uncertainty could mean that 100% of badgers could be potentially removed from an area.

Simon King started by quoting the ISG report, and went on to discuss the potential for other wildlife, such as deer, to become reservoirs of bTB if badgers are culled. He highlighted the need for stricter biosecurity measures between farms to help show the effectiveness of programmes of badger vaccination carried out by regional Wildlife Trusts. The complex epidemiology of the disease was noted, and research from Lion Aid highlighted the potential need for fine-scale molecular analysis of the bacterium.

The issue of cattle vaccination was brought up throughout the debate by both panellists and questions from Parliamentarians. Currently, European legislation restricts the use of vaccines against bTB on cattle, due to the inability to differentiate between infected and vaccinated cattle. There are also concerns that the currently available vaccine (BCG) would not confer full protection. Sir Jim Paice drew attention to a letter recently received by the Secretary of State, Owen Paterson, from EU Health Commissioner Tonio Borg, that outlined the EU’s timescales for developing a cattle vaccine for bTB. A ‘tentative timeline’ shows that an implemented vaccine is at least 10 years away, if long-term trials are initiated this year. All on the panel felt this provided a block to the management of the disease in the UK, and were keen to try and push this timetable forward.

The debate was a good forum for those on both sides of badger culling to present their views. Brian May’s comments on the evaluation and of and use of data from the pilot culls were especially pertinent and highlighted the lack of scientific rigour throughout this policy.